Color sensing for laser decoating

ABSTRACT

A coating removal apparatus utilizing a common optics path to provide laser pulses and light illumination to a coated surface. Reflected light resulting from the light illumination impinging the coated surface is directed to a photosensitive detector and analyzer. The reflected light is either sensed directly from the coated surface by the photosensitive detector or the reflected light is directed along at least a portion of the common optics path to the photosensitive detector. The apparatus is an integrated device including a laser source, a beam splitter, scanning optics, a waste removal apparatus, one or more light illuminators, a photosensitive detector, a comparator, and a control logic circuit. Alternatively, the coating removal apparatus is configured as a head component coupled to a body component.

RELATED APPLICATIONS

This application claims priority of U.S. provisional application, Ser. No. 60/713,886, filed Sep. 2, 2005, and entitled “Color Sensing for Laser Decoating,” by the same inventors. This application incorporates U.S. provisional application, Ser. No. 60/713,886, filed Sep. 2, 2005, and entitled “Color Sensing for Laser Decoating” in its entirety by reference.

This application is also a continuation-in-part of U.S. patent application Ser. No. 11/030,710, filed Jan. 5, 2005 now U.S. Pat. No. 7,633,033, and entitled “Color Sensing for Laser Decoating.” This application incorporates U.S. patent application Ser. No. 11/030,710, filed Jan. 5, 2005, and entitled “Color Sensing for Laser Decoating,” in its entirety by reference. The U.S. patent application Ser. No. 11/030,710 claims priority of U.S. Provisional Application, Ser. No. 60/535,725, filed Jan. 9, 2004, and entitled “Color Sensing for Laser Decoating.” This application incorporates U.S. Provisional Application, Ser. No. 60/535,725, filed Jan. 9, 2004, and entitled “Color Sensing for Laser Decoating” in its entirety by reference.

FIELD OF THE INVENTION

The invention relates to ablating a coating using a laser. In particular, the invention relates to removing a coating from a surface using a laser and color sensing system.

BACKGROUND OF THE INVENTION

Delivery of certain wavelengths of radiant energy is facilitated by transmission along flexible silica fibers. The energy is dispersed from the emitting end of an optical fiber in a widening cone. The energy intensity is generally symmetric about the central fiber axis (e.g., uniformly distributed in azimuth) at the emitting end. The distribution of emitted energy orthogonal to the azimuth angle is highly non-uniform, with highest intensity at the central axis, rapidly decreasing with increasing divergence angle relative to the central fiber axis, sometimes approximated by a power cosine function of the divergence angle.

Energy beam guiding structures are known that use refractive media (e.g. optical lenses) in combination with movable reflective media (e.g. mirrors) to focus and direct diverging radiant energy disposed around the input beam axis to a target of interest. The optical lenses typically convert (collimate) the dispersing radiant energy to a second beam with the radiant energy directed more parallel to the input beam axis. The second beam's energy is distributed over a cross-sectional area defined on a target surface oriented in a transverse plane intersecting the optical axis of the second beam. The size of the defined area is typically limited by the diameter of the lenses. The movable reflective media are coupled to transporting mechanisms and are positioned to modify the direction of the collimated beam as a function of time, typically in a raster pattern scan mode. The dynamic positioning of the reflective media is generally arranged so that the energy of the second beam, averaged over a multiple number of scan cycles, is distributed as a less intense, more uniform energy intensity distribution over the desired target surface area. In addition, one or more condensing (focusing) lens can be used to focus the collimated beam energy to a fine point at the target's surface. Combinations of mirrors, prisms, and/or lenses are used to achieve both effects. The typical objective of these combined reflective and refractive elements is to modify the beams intensity distribution over the width of a limited transverse area and to move the scan area over a target surface to produce a less intense, more uniform, energy intensity distribution over a larger area.

In previous laser scanning heads, the beam is typically reflected from two raster scanning mirrors movably mounted in a housing where they are disposed with the first mirror intercepting the input beam, reflecting it to the second mirror, which then reflects the beam toward the target. In other previous laser scanning heads, the beam is refracted through moving optical components to direct the beam toward the target.

Laser-based coating removal systems use pulses of light from high power lasers to ablate or vaporize the paint or other coating from a surface. Each pulse removes the coating from a small region, typically 0.1 to 100 square mm. The laser is pointed to a different area after each pulse, where the removal process is repeated until the entire surface is cleaned.

An advantage of lasers for coating removal is that each laser pulse removes a predictable portion of the thickness of the coating, in the small region impacted by the pulse. This opens the possibility of selective stripping where, for example, the topcoat could be removed but not the primer.

There have been previous designs using color as a selection criterion for selective stripping, such as U.S. Pat. Nos. 5,643,476, and 6,288,362, as well as U.S. patent application Ser. No. 10/272,329. These conventional processes utilize a television camera to observe the field being stripped and a computer to analyze the image. The drawback of this approach is the difficulty in maintaining the correspondence between the TV field of view and that of the laser scanner. Any curvature or movement of the surface causes a mismatch between the camera and laser scanning coordinates. This results in a failure to strip desired locations as well as stripping undesired locations.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a coating removal apparatus for and a method of removing a coating from a surface. Laser scanning optics preferably also function as the illumination path for a light illumination directed onto the surface. The light illumination is reflected off the surface and collected by a color sensor to achieve a known correspondence between the scanning optics conditions and the local surface color parameters.

The positions of focusing and scanning optics determine a laser light path to a target location on the coated surface. Immediately prior to firing the laser light pulse onto the target position, illumination is provided along an illumination path to the target position on the surface by one or more illuminators. The illumination path preferably includes at least a portion of the laser light path. In some embodiments, the illumination path includes the focusing and scanning optics included in the laser light path. The illumination is reflected at the surface. The light illumination path is configured such that the light illumination impinges the target location at an illumination angle. The illumination angle is measured from the perpendicular to the surface at the target location. In some embodiments, a detector is positioned to collect the reflected light directly from the surface. The detected illumination signal is then compared with the specifications and this signal is used to determine whether to fire the laser at this particular target location. The detector is positioned at a sensor angle, where the sensor angle is measured in an opposite direction from the perpendicular to the surface at the target location. Alternatively, the reflected light is collected by the scanning and focusing optics. In this alternative embodiment, the reflected light is separated from the laser path at some location and sent to a photosensitive detector. A beam splitter can be used to re-direct the reflected light from the laser path to the photosensitive detector.

There are several variations possible for implementing this design. In one configuration, the scanning optics include mirrors, also known as reflecting scanners. In another configuration, the scanning optics include refracting scanners where the light is deflected by transmissive optics. Other variations are directed to the illumination that provides the reflected light. Preferably, the illumination is provided via the focusing and scanning optics and the detector collects the reflected light directly from the surface. Alternatively, the reflected light is directed back through the focusing and scanning optics, where it is eventually split from the laser path to the detector.

Preferably, the laser source is coupled to the focusing optics. Alternatively, the laser source is coupled to the focusing and scanning optics via a fiber optic cable. In this alternative configuration, the beam splitter, the illuminator, and in some embodiments the detector, are located at the laser end of the fiber optic cable.

The illumination and detection process can be accomplished in several manners. It can vary from the simplicity of a single sensor and illumination at either a single or wide range of wavelengths. In such a configuration, the single detector with a wide spectrum illuminator constitutes a grayscale sensor measuring only the relative lightness of the surface. At the more complex end of the scale, a spectrophotometer sensor measures the reflectance at hundreds of different wavelengths. In the preferred embodiment, two colors, red and blue, are used for measurement.

The colors can be separated in various ways. One approach uses filters to separate the colors, where each separated color is sent to a corresponding detector. Another technique is to separate the colors using a grating. In the preferred embodiment, a single detector is used and the colors are separated temporally. Using this preferred approach, the red illuminator is energized and the red measurement made, then the blue illuminator is energized and the blue measurement made through the same detector. Alternatively, the blue illuminator is energized and the blue measurement made, then the red illuminator is energized and the red measurement made.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a coating removal device according to an embodiment of the present invention.

FIG. 2 illustrates a block diagram of a coating removal device according to another embodiment of the present invention.

FIG. 3 illustrates a coating removal system including a first configuration of the scanning optics.

FIG. 4 illustrates a coating removal system including a second configuration of the scanning optics.

FIG. 5 illustrates a block diagram of a coating removal device according to yet another embodiment of the present invention.

FIG. 6 illustrates an exemplary coating removal pattern.

FIG. 7 illustrates a coating removal device according to another embodiment of the present invention.

FIG. 8 illustrates a coating removal device according to another embodiment of the present invention.

FIG. 9 illustrates a coating removal device according to another embodiment of the present invention.

FIG. 10 illustrates a coating removal device according to another embodiment of the present invention.

FIG. 11 illustrates the coating removal system of FIG. 10 including an exemplary configuration of the scanning optics.

Embodiments of the coating removal device are described relative to the several views of the drawings. Where appropriate and only where identical elements are disclosed and shown in more than one drawing, the same reference numeral will be used to represent such identical elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Embodiments of the present invention are directed to an apparatus for and a method of utilizing various optics paths to provide laser pulses to a coated surface, to direct a light illumination to the coated surface, and to direct the reflected light from the coated surface to a photosensitive detector and analyzer. Preferably, the apparatus is an integrated device including a laser source, a beam splitter, scanning optics, a waste removal apparatus, one or more light illuminators, a photosensitive detector, a comparator, and a control logic circuit. Alternatively, the laser source is external to the integrated device and a fiber optic cable is used to connect the laser source to the integrated device.

The focusing and scanning optics are positioned such that a laser light path is directed to a first position on the coated surface. Immediately prior to firing a laser light pulse on the first position of the coated surface, illuminators provide illumination which is directed to the first position of the coated surface. In some embodiments, the light illumination is provided along a light illumination path that includes the focusing and scanning optics. In other embodiments, the light illumination is provided directly onto the surface. The illumination is reflected and either collected by the focusing and scanning optics and separated from the laser path at some location by the beam splitter, or collected directly from the coated surface. The reflected light is directed to the photosensitive detector. The comparator compares the reflected light detected by the photosensitive detector to predefined specifications in order to determine whether or not to fire the laser at the first position on the coated surface.

The control logic circuit provides control signals to the laser source to generate each laser pulse. The control logic circuit also provides control signals to the scanning optics such that the scanning optics are properly aligned to direct the laser pulse, and in some embodiments the light illumination, to a determined position on the coated surface. After the laser pulse impinges the coated surface, the control logic circuit sends control signals to the scanning optics to realign themselves such that a subsequent laser pulse, and in some embodiments the light illumination, is directed to a second position on the coated surface. After the scanning optics are realigned, the control logic circuit sends a control signal to the laser source to generate the subsequent laser pulse, which is directed to the second position on the coated surface. Procession over the coated surface continues according to a predetermined coating removal pattern. At each position within the pattern, reflected light is collected and analyzed. At each position, preferably a comparator determines if a sufficient amount of coating has been removed. If it is determined that a sufficient amount of coating has not yet been removed, then a laser pulse is preferably fired at that position and then a determination is made of the next position. If it is determined that a sufficient amount of coating has been removed from the position, then the laser pulse is not fired and a determination is made for the next position. This process is repeated for an area until a predetermined percentage of the positions within the area do not require the laser to fire. In this case, the system then moves to the next area. Alternatively, a determination memory is utilized such that if the comparator determines that a sufficient amount of coating has not yet been removed from a position on the coated surface, then the control logic circuit adds the position to a records list such that during a subsequent cycle performed according to the coating removal pattern, a laser pulse is preferably fired only at the positions listed in the records list.

Ablation of the coating causes a waste byproduct. The waste removal apparatus preferably collects the waste byproduct from the ablated surface and directs the collected waste to an externally coupled waste receptacle. Alternatively, the waste removal apparatus includes local storage for the collected waste byproduct.

FIG. 1 illustrates a block diagram of a coating removal device according to an embodiment of the present invention. The coating removal device 10 is an integrated device that includes a laser source 12, a beam splitter 14, scanning optics 16, illuminators 18, a photosensitive detector 20, a comparator 22, a control logic circuit 24, and a waste collector 26. Within FIG. 1, the solid lines between elements represent optical paths and the dashed lines represent data signal paths. The laser source 12 generates a laser pulse, represented as light 30. Light 30 passes through the beam splitter 14 to the scanning optics 16. Within the scanning optics 16, the light 30 is aligned and focused such that the light 30 impinges a specific position 52 on a coated surface 50. A laser scanning path is defined as the path the laser pulse traverses to reach the coated surface 50. In reference to FIG. 1, the laser scanning path includes the path through the beam splitter 14 and the scanning optics 16.

As is well known in the art of laser optics, a surface area of the position 52 onto which the light 30 impinges can be made as small or as large as necessary to perform the desired functionality of ablating the coating at the position 52. Increasing or decreasing the impinging surface area respectively decreases or increases the light intensity delivered onto the surface area. The amount of light intensity is an adjustable parameter which is used to meet various application specifications. It is understood that the light intensity delivered over a given surface area depends not only on the given surface area but also in part to the laser source specifications and loss within the integrated apparatus.

Upon impinging the position 52, the light 30 ablates a portion of the coating corresponding to the position 52. It is anticipated that each laser pulse removes a uniform amount of coating. The amount of coating removed includes the surface area impinged by the light 30 and a depth of the coating at the position 52. An anticipated depth can be calculated based on the intensity of the light 30, the surface area impinged, the nature of the coating, etc. In operation, the actual depth of the coating that is removed can vary from the calculated depth. Underneath the coating to be removed is either a different coating (an undercoating) comprising a different material or a different color, or the original surface material to which the coating was originally applied. In either case, it is anticipated that the undercoating or original surface reflects a wavelength of light different than that reflected by the coating being removed. As such, it can be determined if the coating to be removed is in fact completely removed by measuring a wavelength of light reflected off the position 52. The illuminators 18 provide a light illumination 32 to the position 52 on the coated surface 50. Light illumination 32 is reflected off the position 52 as reflected light 34 and through the scanning optics 16 to the beam splitter 14. At the beam splitter 14, the reflected light 34 is split, or re-directed, from the laser scanning path as re-directed reflected light 36. The light 36 is directed to the photosensitive detector 20 where characteristics of the reflected light are measured. Data corresponding to the measured characteristics is sent from the photosensitive detector 20 to the comparator 22 via a data line 40.

A color sensing path is defined as the path the reflected light traverses from the coated surface 50 to the photosensitive sensor 20. In reference to FIG. 1, the color sensing path includes the path through the scanning optics 16 and the beam splitter 14. In the coating removal device 10, the color sensing path includes the optics that comprises the laser scanning path.

The comparator 22 compares the measured characteristics of the reflected light to previously defined parameters and thresholds. The previously defined parameters and thresholds can be internally stored within the comparator 22, or they can be received from a separate memory for the purposes of being used in the comparison operation. The memory is preferably a conventional memory type located within the integrated device 10. Included within the previously defined parameters are characteristics of the coating to be removed, for example the coating color.

The results of the comparison made by the comparator 22 are sent to the control logic circuit 24 via a data line 42. The comparison determines if the coating is sufficiently removed from the position 52. To make this determination, the wavelength of the reflected light is measured. The reflected light wavelength indicates a color of a top layer of the coated surface 50 at the position 52 after the portion of coating has been ablated by the impinging light 30. If this measured top layer color is substantially the same as a color of the coating to be removed, as defined by the stored coating parameters, then it is determined that a portion of the coating to be removed still remains at the position 52. In this case, the laser pulse is then fired at this position and the system then moves to the next position. This process is repeated for an area until a predetermined percentage of the positions within the area do not require the laser to fire. In this case, the system then moves to the next area.

If the comparison performed by the comparator 22 determines that the top layer color is substantially different than the previously defined coating color, then it is concluded that directing another laser pulse onto the position 52 is not necessary. After the laser pulse impinges the position 52, or it is determined that firing the laser pulse at the position is not necessary, the control logic circuit 24 sends a control signal to the scanning optics 16 via a data line 44, the control signal instructs the scanning optics 16 to realign such that a subsequent laser pulse is directed to a position on the coated surface 50 different than the position 52. After the scanning optics 16 are realigned to a subsequent position, a determination is then made as to whether or not the laser pulse should be fired at the new position.

In one embodiment, as the scanning optics 16 are realigned, a delay in the color sensing circuit causes an offset between the color sensing location, such as position 52, and the subsequent firing location. If this error is too large, performance may be inadequate. A solution to this problem is to offset the position of the color sensing relative to the stripping position, to provide a look ahead function. Considerations are made for situations where the scanning direction or speed is changed. In these situations, the color sensor is moved to change the offset or multiple sensors are used for different scan speeds and directions.

Although not shown in the figures, individual optical elements within the scanning optics 16 are aligned using any conventional means for physically moving one or more of the individual optical elements. For example, drive gears are connected to the optical elements and a motor is connected to the drive gears. In this example, control signals sent by the control logic circuit 24 provide instructions as to the movement of the drive gears using the motor.

The waste collector 26 collects the waste byproduct resulting from the laser pulse impinging the coated surface 50 and ablating the top layer coating. The waste collector 26 includes a local storage for storing the collected ablated waste byproduct. An alternative waste collector acts as a waste removal apparatus and is coupled to an external waste receptacle such that the collected waste byproduct is transported to the external waste receptacle, as shown in FIG. 2. Operation of the waste collector is described in more detail below.

FIG. 2 illustrates a coating removal device 100 according to another embodiment of the present invention. The coating removal device 100 includes a head component 110 and a body component 120. The body component 120 includes a laser source 122 and a waste receptacle 124. A fiber optic cable 116, a waste transport tube 114, and a data line 118 couple the body component 120 to the head component 110. In some embodiments, the fiber optic cable 116, the waste transport tube 114, and the data line 118 are all bundled together as a single link. The body component 120 also provides power to the head component 110 via a power line (not shown). The power line is also included within the bundled link between the body component 120 and the head component 110. Alternatively, the head component 110 includes a power source (not shown) that is independent of the power source of the body component 120.

The head component 110 includes the beam splitter 14, the scanning optics 16, the illuminators 18, the photosensitive detector 20, the comparator 22, and the control logic circuit 24 which operate the same as described above in relation to FIG. 1. The fiber optic cable 116 provides the light 30 (laser pulse) from the laser source 122. The control logic circuit 24 provides control signals to the laser source 122 via the data line 118, in a manner similar to that described above in which the control logic circuit 24 provides control signals to the laser source 12 (FIG. 1) via data line 46 (FIG. 1).

Illumination, as provided by the illuminators 18, and detection of the resulting reflected light, as performed by the photosensitive detector 20, can be accomplished in several different manners. The illuminators can be comprised of one to many individual illuminators that provide illumination from a single wavelength to a wide range of wavelengths. Similarly, the photosensitive detector 20 can comprise one to many sensors for detecting light. One method using a single sensor with a wide spectrum illuminator, constitutes a grayscale sensor that measures the relative lightness of a surface. Another method uses a spectrophotometer sensor that measures a reflectance at hundreds of different wavelengths. The use of multiple sensors allows the sensing to compensate for variations in the tilt of the surface being ablated. Multiple sensors can also be combined with multiple wavelengths. In some embodiments, two color illumination and sensing is implemented where the two colors are red and blue. In this case, the configuration of the illuminators 18 includes two red illuminators and two blue illuminators. Alternatively, more or less than two illuminators can be used. In some embodiments, one or more red illuminators, one or more blue illuminators, and one or more green illuminators are used. It is contemplated that any illumination and sensing techniques can be used that enables the coating removal system to determine the color of a top layer of a coated surface.

The illumination colors can be separated using any conventional technique. One approach uses filters within the photosensitive detector such that the filters separate the colors and send each separated color to a corresponding sensor. Another approach is to separate the colors using a grating. In yet another approach, color separation is performed using a single sensor within the photosensitive detector 20 and separating the colors temporally. To accomplish this in the case of red illuminators and blue illuminators, the red illuminators are energized and the corresponding reflected light is measured by the sensor in the photosensitive detector 20. Then, the blue illuminators are energized and the corresponding reflected light is measured by the same sensor. The order can be reversed such that the blue light is measured prior to the red light.

Referring again to FIG. 2, the head component 110 also includes a waste collector 112, which is coupled to the waste transport tube 114. The waste collector 112 collects the waste byproduct resulting from a laser pulse impinging the coated surface 50. The collected waste byproduct is transported through the waste transport tube 114 to the waste receptacle 124. In some embodiments, the waste collector 112 and the waste collector 26 (FIG. 1) are of the type described in the co-owned, co-pending U.S. patent application Ser. No. 10/272,329, filed on Oct. 15, 2002, and entitled “Laser Scanning Head with Rotary Scanning Coaxial Refractive Optics,” which is hereby incorporated by reference.

In some embodiments, impact of the focused laser beam on the target surface ejects ablation products in a direction generally counter to the direction of the incident beam. This waste byproduct enters the head component 110 at an exit aperture of a nosepiece (not shown) and mixes internally with a purge-gas stream. The nosepiece is shaped internally to redirect the purge stream after it picks up the waste byproducts. The exiting waste stream is directed rearward in the nosepiece to a passageway within the housing. The passageway delivers the purge flow to the waste transport tube 114 for transport to the waste receptacle 124 in the body component 120. A vacuum blower (not shown) in the body component 120 draws the purge flow through the service hose.

A converging nozzle internal to the nosepiece is mounted facing adjacent to the exit aperture. The exhaust stream draws a protective high-speed airflow through the nozzle toward the exit aperture to prevent the gases and particles from the target spot from reaching and contaminating the scanner optics and drive gears used to move the scanning optics.

The purge gas is supplied through a tubular inlet on the side housing of the head component 110. A hose connected to a remote equipment unit supplies non-combustible gases, or, if allowed in the work area, the inlet is open to ambient air.

A more detailed description of an exemplary waste collector 26, 112 is described in the previously referenced U.S. patent application Ser. No. 10/272,329.

Numerous different optical configurations can be used within the scanning optics 16 (FIGS. 1 and 2) to direct the light 30 to the coated surface 50 and to direct the reflected light 34 from the coated surface 50 the beam splitter 14. One such configuration, as shown in FIG. 3, includes the use of focusing optics and reflecting scanners, for example mirrors. Another configuration, as shown in FIG. 4, utilizes focusing optics and refracting scanners, such as prisms. It is understood that the scanning optics 16 have the ability to be optically configured in any number of different configurations, using any number of optical elements, such that the scanning optics 16 direct a laser light pulse from a first optical position (such as the beam splitter 14) to the coated surface and direct a reflected light from the coated surface back to the first optical position.

FIG. 3 illustrates a coating removal system including a first configuration of the scanning optics. The scanning optics 16 (FIGS. 1 and 2) include focusing optics 202 and 208, and reflecting scanners 204 and 206. The first configuration of the scanning optics 16 is shown in FIG. 3 as being applied to the coating removal system 100 (FIG. 2). The first configuration can be equally applied to the coating removal system 10 (FIG. 1). For simplicity, not all elements of the coating removal system 100 are shown in FIG. 3.

The focusing optics 202 collimate the light 30 and direct the collimated light to the reflecting scanner 204. The light 30 is reflected by the reflecting scanners 204 and 206 to the focusing optics 208. The focusing optics 208 direct and focus the light 30 to a position, such as position 52, on the coated surface 50. The exact position on the coated surface 50, and the dimensions of the light impinging the coated surface 50, are determined by the alignments of the focusing optics 202, the reflecting scanners 204 and 206, and the scanning optics 208, which are controlled by control signals sent by the control logic circuit 24. Although the focusing optics 202 and 208 are shown in FIG. 3 as single elements, it should be clear to those skilled in the art that either or both of the focusing optics 202 and 208 can comprise one or more optical elements. Similarly, although two reflecting scanners 204 and 206 are shown in FIG. 3, it should be clear that more, or less than two reflecting scanners can be used.

FIG. 3 also illustrates a first configuration of the illuminators 18. In this first configuration, the light illuminators 18 include two red illuminators 212 and two blue illuminators 214.

FIG. 4 illustrates a coating removal system including a second configuration of the scanning optics. The coating removal system shown in FIG. 4 is the same as the coating removal system of FIG. 3 except that the focusing optics 202, reflecting scanners 204 and 206, and focusing optics 208 of FIG. 3 are replaced by focusing optics 302, refracting scanners 304 and 306, and focusing optics 308. The focusing optics 302 collimate the light 30 and direct the collimated light to the refracting scanner 304. The light 30 is refracted by the refracting scanners 304 and 306 to the focusing optics 308. The focusing optics 308 direct and focus the light 30 to a position, such as position 52, on the coated surface 50. The exact position on the coated surface 50, and the dimensions of the light impinging the coated surface 50, are determined by the alignments of the focusing optics 302, the refracting scanners 304 and 306, and the scanning optics 308, which are controlled by control signals sent by the control logic circuit 24. Exemplary operation of the focusing optics 302 and 308, and the refracting optics 304 and 306 is described in the previously referenced U.S. patent application Ser. No. 10/272,329. Although the focusing optics 302 and 308 are shown in FIG. 4 as single elements, it should be clear to those skilled in the art that either or both of the focusing optics 302 and 308 can comprise one or more optical elements. Similarly, although two refracting scanners 304 and 306 are shown in FIG. 4, it should be clear that more, or less, than two reflecting scanners can be used.

Although the scanning optics 16 are described according to the first configuration including focusing optics and reflecting scanners, and according to the second configuration including focusing optics and refracting scanners, it is also contemplated that the scanning optics 16 can comprise any combination of focusing optics, reflecting scanners, and refracting scanners. It is also contemplated that although FIGS. 3 and 4 each show two different sets of focusing optics, 202/208 and 302/308, each of the two sets can be replaced by a single set of focusing optics.

FIG. 5 illustrates an alternative configuration of a coating removal device 300. In this alternative configuration, the beam splitter 14, the photosensitive detector 20, the comparator 22, and the control logic circuit 24 are located in a body component 320 (instead of in the head component as in the head component 110 of coating removal device 100 of FIG. 2). The coating removal device 300 operates in a similar manner as the coating removal device 100 (FIG. 2) except that reflected light 34 is directed to the body component for detection and analysis. The control logic circuit 24, located in the body component 320 of FIG. 5, sends control signals to the scanning optics 16 in the head component 310 via data line 330. Focusing optics 322 are included in the body component 320 to focus the light 30 into a first end of the fiber optic cable 116. The focusing optics 322 also direct the reflected light 34 received from the fiber optic cable 116 to the beam splitter 14.

In a manner similar to that of coating removal device 300, it is contemplated that the coating removal device 10 (FIG. 1) can be adapted such that the laser source 12 and the beam splitter 14 are optically coupled to the scanning optics 16 via a fiber optic cable. In such a configuration, the photosensitive detector 20 can be positioned at the laser source end of the fiber optic cable.

In operation, a coating removal device directs a laser pulse to a predetermined position on a coated surface. The laser pulse is directed to the predetermined position according to a laser path which includes a beam splitter, focusing optics, and scanning optics. The laser pulse, upon impinging the predetermined position, ablates some or all of the coating at the predetermined position. To determine if a proper amount of coating is removed from the predetermined position, light illuminators provide light illumination to the predetermined position. Reflected light resulting from the light illumination is directed along a color sensing path to a photosensitive detector. In some embodiments, the color sensing path includes some or all of the optical components of the laser path. The beam splitter re-directs the reflected light from the laser path to the photosensitive detector where measurements are taken. These measurements are sent from the photosensitive detector to a comparator where an analysis is made that compares characteristics of the detected light to predefined parameters and thresholds.

A color of the reflected light is measured and compared to a known color of the coating that is to be removed. If the comparator determines that the detected light is of the same color as the known color, then it is concluded that coating still remains at the predetermined position on the coated surface. In this case, the laser pulse is fired at the predetermined position. If the comparator determines that the detected light is not the same color as the known color, then it is concluded that coating no longer remains at the predetermined position on the coated surface, and as such, the laser pulse does not need to be fired at the position. In either case, the control logic circuit instructs the focusing and scanning optics to realign to a next position on the coated surface.

Coating that is ablated by an impinging laser pulse is collected as waste byproduct by a waste removal mechanism. The waste removal mechanism can be integrated within a common head assembly that includes the laser and color sensing optical paths.

As described in detail above, each laser pulse generated by the laser source is directed to a predetermined position on the coated surface. After the coating is removed from a first position, the control logic circuit instructs the focusing and scanning optics to align themselves such that a subsequent laser pulse is directed to a second position different than the first position. In most applications, the coating is removed from the entire coated surface. That is, if the coated surface comprises a 10 feet by 10 feet surface area, then the coated surface is removed over the entire 100 square feet. In this case, it is most efficient to remove coating from progressively adjacent positions. In other words, where the second position is located adjacent to the first position. However, this is not always the case. In some applications, it is not desired that the entire surface area is to be removed of coating. Instead, only portions of the surface area are to have the coating removed. The exact pattern of the coating to be removed can be any desired pattern. The control logic circuit determines the desired pattern according to a stored algorithm or program.

FIG. 6 illustrates an exemplary coating removal pattern. The larger box represents a coated surface with a surface area of 7 units by 7 units. The shadowed boxes, which are the odd numbered boxes, represent those positions on the coated surface at which the coating is to be removed. The clear boxes, which are the even numbered boxes, represent those positions on the coated surface at which the coating is not to be removed. If the coating removal system starts removing coating at the box 1, then after the coating is removed, the next position to which the focusing and scanning optics will align is one of the odd numbered boxes. In most circumstances, the next position would be either box 3, 9, or 15, although the exact sequence, as well as the starting position can vary. In this manner, the coated surface can be “roughed up”, where only certain positions on the coated surface have the coating removed.

FIGS. 1-5 each show illumination provided directly at the coated surface 50 by the illuminators 18. It is also contemplated within the present invention that the illuminators can be positioned such that the illumination provided by the illuminators 18 is directed through the scanning optics 16. It is also contemplated that the illumination provided through the scanning optics 16 can be detecting by a photosensitive detector collecting reflected light directly from the coated surface 50.

FIG. 7 illustrates a coating removal device 400 according to another embodiment of the present invention. The coating removal device 400 provides a similar function as the coating and removal device 10 (Figure), however, the coating removal device 400 is configured such that the light illumination is directed through the scanning optics and the reflected light is collected directly from the coated surface. The coating removal device 400 is an integrated device that includes a laser source 412, a laser mirror 406, scanning optics 416, one or more illuminators 418, a mirror 404, a photosensitive detector 420, a comparator 422, a control logic circuit 424, and a waste collector 426. The laser source 412 operates similarly as the laser source 12 (FIG. 1) to generate a laser pulse, represented as light 430. Light 430 is reflected off the laser mirror 406 to the scanning optics 416. Within the scanning optics 416, the light 430 is aligned and focused such that the light 430 impinges a specific position, such as the position 52, on the coated surface 50. In reference to FIG. 7, the laser scanning path includes the laser mirror 406 and the scanning optics 416. Upon impinging the position 52, the light 430 ablates a portion of the coating corresponding to the position 52.

The illuminators 418 provide a light illumination 432 to the position 52 on the coated surface 50. Light illumination 432 is reflected off the position 52 as reflected light 434. The reflected light 432 is collected by the photosensitive detector 420 where characteristics of the reflected light are measured. Data corresponding to the measured characteristics is sent from the photosensitive detector 420 to the comparator 422 via a data line 440.

In reference to FIG. 7, the color sensing path is the path from the surface 50 of the photosensitive detector 420. In the coating removal device 400, the color sensing path is separate from the laser scanning path and the light illumination path.

The comparator 422 operates similarly to the comparator 22 (FIG. 1). The results of the comparison made by the comparator 422 are sent to the control logic circuit 424 via a data line 442. The comparison determines if the coating is sufficiently removed from the position 52. If the coating is not sufficiently removed from the position 52, the laser pulse is again fired at the position 52. If the coating is sufficiently removed from the position 52, then the system is realigned. To realign the system, the control logic circuit 424 sends a control signal to the scanning optics 416 via a data line 444, the control signal instructs the scanning optics 416 to realign such that a subsequent laser pulse is directed to a position on the coated surface 50 different than the position 52. After the scanning optics 416 are realigned to a subsequent position, a determination is then made as to whether or not the laser pulse should be fired at the new position.

Although not shown in the figures, individual optical elements within the scanning optics 416 are aligned using any conventional means for physically moving one or more of the individual optical elements. For example, drive gears are connected to the optical elements and a motor is connected to the drive gears. In this example, control signals sent by the control logic circuit 424 provide instructions as to the movement of the drive gears using the motor.

The waste collector 426 collects the waste byproduct resulting from the laser pulse impinging the coated surface 50 and ablating the top layer coating. The waste collector 426 operates in a manner similar to that of the waste collector 26 (FIG. 1).

FIG. 8 illustrates a coating removal device 500 according to another embodiment of the present invention. The coating removal device 500 includes a head component 510 and a body component 520. The body component 520 includes the laser source 412 and a waste receptacle 524. A fiber optic cable 516, a waste transport tube 514, and a data line 546 couple the body component 520 to the head component 510. In some embodiments, the fiber optic cable 516, the waste transport tube 514, and the data line 546 are all bundled together as a single link. The body component 520 also provides power to the head component 510 via a power line (not shown). The power line is also included within the bundled link between the body component 520 and the head component 510. Alternatively, the head component 510 includes a power source (not shown) that is independent of the power source of the body component 520.

The head component 510 includes the laser mirror 406, the scanning optics 416, the illuminators 418, the mirror 404, the photosensitive detector 420, the comparator 422, and the control logic circuit 424 which operate the same as described above in relation to FIG. 7. The fiber optic cable 416 provides the light 430 (laser pulse) from the laser source 412. The control logic circuit 424 provides control signals to the laser source 412 via the data line 546, in a manner similar to that described above in which the control logic circuit 424 provides control signals to the laser source 412 (FIG. 7) via data line 446 (FIG. 7).

The illuminators can be comprised of one to many individual illuminators that provide illumination from a single wavelength to a wide range of wavelengths. As with the photosensitive detector 20 (FIG. 1), the photosensitive detector 420 can comprise one to many sensors for detecting light. One method using a single sensor with a wide spectrum illuminator, constitutes a grayscale sensor that measures the relative lightness of a surface. Another method uses a spectrophotometer sensor that measures a reflectance at hundreds of different wavelengths. In some embodiments, two color illumination and sensing is implemented where the two colors are red and blue. In this case, the configuration of the illuminators 418 includes a red illuminator and a blue illuminator. Alternatively, more or less red and blue illuminators can be used. Still alternatively, more or less than two colors of illuminators can be used. In some embodiments, one or more red illuminators, one or more blue illuminators, and one or more green illuminators are used. It is contemplated that any illumination and sensing techniques can be used that enables the coating removal system to determine the color of a top layer of a coated surface.

The illumination colors can be separated using any conventional technique. One approach uses filters within the photosensitive detector such that the filters separate the colors and send each separated color to a corresponding sensor. Another approach is to separate the colors using a grating. In yet another approach, color separation is performed using a single sensor within the photosensitive detector 420 and separating the colors temporally. To accomplish this in the case of a red illuminator and a blue illuminator, the red illuminator is energized and the corresponding reflected light is measured by the sensor in the photosensitive detector 420. Then, the blue illuminator is energized and the corresponding reflected light is measured by the same sensor. The order can be reversed such that the blue light is measured prior to the red light.

Referring again to FIG. 8, the head component 510 also includes a waste collector 562, which is coupled to the waste transport tube 514. The waste collector 526 collects the waste byproduct resulting from a laser pulse impinging the coated surface 50. The collected waste byproduct is transported through the waste transport tube 514 to the waste receptacle 524. The waste collector 526 and the waste receptacle function in a manner similar to the waste collector 112 and the waste receptacle 124 (FIG. 2), respectively.

FIG. 9 illustrates a coating removal device 600 according to another embodiment of the present invention. In the coating removal device 600, the laser mirror 406, the mirror 404, the illuminators 418, and the control logic circuit 424 are located in a body component 620 (instead of in the head component as in the head component 510 of coating removal device 500 of FIG. 8). The coating removal device 600 operates in a similar manner as the coating removal device 500 (FIG. 8) except that the light illumination 432 is generated in the body component and directed to the head component via the fiber optic cable. The control logic circuit 424, located in the body component 620 of FIG. 9, sends control signals to the scanning optics 416 in the head component 610 via data line 644. The control logic circuit 424 also sends control signals to the comparator 422 via data line 642. Focusing optics 622 are included in the body component 620 to focus the light 430 into a first end of the fiber optic cable 516.

In a manner similar to that of coating removal device 600, it is contemplated that the coating removal device 400 (FIG. 7) can be adapted such that the laser source 412 and the laser mirror 406 are optically coupled to the scanning optics 416 via a fiber optic cable. In such a configuration, the coating removal device 400 remains an integrated device and the illuminators 418 can be positioned at the laser source end of the fiber optic cable.

FIG. 10 illustrates a coating removal device 700 according to another embodiment of the present invention. The coating removal device 700 is an integrated device that includes the laser source 412, the laser mirror 406, scanning optics 716, the one or more illuminators 418, the mirror 404, a beam splitter 704, the photosensitive detector 420, the comparator 422, the control logic circuit 424, and the waste collector 426. The coating removal device 700 provides a similar function as the coating and removal device 400 (FIG. 7), except that the coating removal device 700 is configured such that the reflected light 734 from the surface 50 is directed back through the scanning optics 716. The reflected light 734 is then redirected by the beam splitter 704 to the photosensitive detector 420. In reference to FIG. 7, the laser scanning path includes the laser mirror 406, the beam splitter 704, and the scanning optics 716. The color sensing path is the path from the surface 50 to the photosensitive detector 420, including the scanning optics 716 and the beam splitter 704. In the coating removal device 700 of FIG. 10, the color sensing path, the laser scanning path, and the light illumination path all include the scanning optics.

Although the coating removal device 700 is shown in FIG. 10, and described above, as an integrated device, the coating removal device 700 can also be configured as a head component and a body component in a manner similar to that of the coating removal device 500 (FIG. 8) and coating removal device 600 (FIG. 9). It is also contemplated that the coating removal device 700 can be adapted such that the laser source 412 and the laser mirror 406 are optically coupled to the scanning optics 716 via a fiber optic cable. In such a configuration, the coating removal device 700 remains an integrated device and the illuminators 418 can be positioned at the laser source end of the fiber optic cable.

FIG. 11 illustrates the coating removal system 700 including an exemplary configuration of the scanning optics 716 (FIG. 10). The scanning optics 716 include focusing optics 708, such as a telecentric scanning lens, and reflecting scanners 704 and 706. The light 30 is reflected by the reflecting scanners 704 and 706 to the focusing optics 208. The focusing optics 708 direct and focus the light 430 to a position, such as position 52, on the coated surface 50. The exact position on the coated surface 50, and the dimensions of the light impinging the coated surface 50, are determined by the alignments of the scanning optics 708 and the reflecting scanners 704 and 706, which are controlled by control signals sent by the control logic circuit 424. Although the focusing optics 708 are shown in FIG. 11 as single elements, it should be clear to those skilled in the art that the focusing optics 708 can comprise one or more optical elements. Similarly, although two reflecting scanners 704 and 706 are shown in FIG. 11, it should be clear that more, or less than two reflecting scanners can be used.

FIG. 11 also illustrates an exemplary configuration of the illuminators 18. In this configuration, the light illuminators 18 include a red illuminator 408 optically coupled to a red laser mirror 402 and a blue illuminator 410 optically coupled to a blue laser mirror 404. The red laser mirror 402 directs a red light illumination 431 output from the red illuminator 408 to the scanning optics 716. The blue laser mirror 404 directs a blue light illumination 433 output from the blue illuminator 410 to the scanning optics 716.

In operation, a coating removal device directs a laser pulse to a predetermined position on a coated surface. The laser pulse is directed to the predetermined position according to a laser path which includes a laser mirror, a beam splitter, focusing optics, and scanning optics. The laser pulse, upon impinging the predetermined position, ablates some or all of the coating at the predetermined position. To determine if a proper amount of coating is removed from the predetermined position, light illuminators provide light illumination to the predetermined position. The light illumination is provided along at least a portion of the laser scanning path. In some embodiments, reflected light resulting from the light illumination impinging the coated surface is collected directly from the coated surface by one or more photosensitive detectors. In other embodiments, the reflected light is directed along a color sensing path to the photosensitive detector, where the color sensing path includes some or all of the optical components of the laser scanning path. Measurements are taken by the photosensitive detector. These measurements are sent from the photosensitive detector to a comparator where an analysis is made that compares characteristics of the detected light to predefined parameters and thresholds.

In some embodiments, sensing of the reflected light is facilitated by providing a color sensing path that is different from the laser path. In this case, an alternative coating removal device is configured in which separate optical paths are configured, one for the laser path and one for the color sensing path.

Numerous different optical configurations can be used within the scanning optics to direct the laser light to the coated surface 50, to direct the light illumination to the coated surface 50, and/or to direct the reflected light to the photosensitive detector. One such configuration, as shown in FIGS. 3 and 11, includes the use of focusing optics and reflecting scanners, for example mirrors. Another configuration, as shown in FIG. 4, utilizes focusing optics and refracting scanners, such as prisms. It is understood that the scanning optics can be optically configured in any number of different configurations, using any number of optical elements, such that the scanning optics direct a laser light pulse to the coated surface, direct a light illumination to the coated surface in some embodiments, and/or to direct a reflected light from the coated surface back to the first optical position in other embodiments.

Similarly, the optical paths of the various embodiments described above, including the laser light path, the light illumination path, and the color sensing path, are for exemplary purposes only. It is understood that alternative configurations, including various combinations and numbers of conventional optical elements can be used to achieve the desired functionalities of the coating removal device described above.

The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention. 

1. A laser-based coating removal system to remove a coating from a surface, the system comprising: a. a laser source to provide a laser pulse; b. scanning optics to direct the laser pulse along a laser path to a first position on the surface, whereby the laser pulse impinges the first position on the surface thereby ablating a portion of the coating from the first position; c. one or more light illuminators to provide a light illumination along a light illumination path to the first position on the surface, wherein the light illumination path includes at least a portion of the scanning optics; and d. one or more photosensitive detectors to receive light reflected from the surface as a result of the light illumination impinging the first position on the surface and to measure the reflected light, wherein each photosensitive detector receives the reflected light directly from the surface.
 2. The system of claim 1 further comprising a control logic circuit coupled to the laser source, the scanning optics, and to the one or more photosensitive detectors, wherein the control logic circuit is configured to provide control signals to the laser source, the scanning optics, and the one or more photosensitive detectors.
 3. The system of claim 2 further comprising a comparator coupled to the one or more photosensitive detectors and configured to compare the measured reflected light with predetermined parameters to determine if the coating is removed from the first position on the surface.
 4. The system of claim 3 wherein the control logic circuit is configured to provide a first control signal to the scanning optics to direct the laser pulse to the first position on the surface if it is determined that the coating is not removed from the first position.
 5. The system of claim 4 wherein the first position and each successive position on the surface is determined according to a coating removal pattern.
 6. The system of claim 5 wherein if it is determined that the coating is not removed from the first position, or one or more successive positions, then the control logic circuit is configured to maintain a record list of each position at which the coating is not removed such that an additional laser pulse is directed to each position listed in the record list.
 7. The system of claim 1 wherein the scanning optics include one or more reflecting scanners.
 8. The system of claim 7 wherein the one or more reflecting scanners comprise a lens and mirror array.
 9. The system of claim 1 wherein the scanning optics include one or more refracting scanners.
 10. The system of claim 9 wherein the one or more refracting scanners comprise a lens and prism array.
 11. The system of claim 1 wherein the scanning optics include focusing optics.
 12. The system of claim 1 further comprising an optical fiber coupled between the laser source and the scanning optics to provide the laser pulse from the laser source to the scanning optics and the light illumination from the one or more light illuminators to the scanning optics.
 13. The system of claim 1 wherein the one or more light illuminators comprises a single wide spectrum illuminator.
 14. The system of claim 13 wherein the one or more photosensitive detectors comprise a single sensor configured to measure a relative lightness of the surface.
 15. The system of claim 13 wherein the one or more photosensitive detectors comprises a spectrophotometer sensor configured to measure the reflectance of the reflected light at a plurality of different wavelengths.
 16. The system of claim 1 wherein the one or more light illuminators comprises a red spectrum illuminator configured to provide a red light illumination, a blue spectrum illuminator configured to provide a blue light illumination, and a green spectrum illuminator configured to provide a green light illumination.
 17. The system of claim 16 wherein the one or more photosensitive detectors comprises a single photosensitive sensor configured to temporally separate a reflected red light resulting from the red spectrum illumination, a reflected blue light resulting from the blue spectrum illumination, and a reflected green light resulting from the green spectrum illumination.
 18. The system of claim 16 wherein the one or more photosensitive detectors comprise a red photosensitive detector configured to receive a reflected red light resulting from the red spectrum illumination, a blue photosensitive detector configured to receive a reflected blue light resulting from the blue spectrum illumination, and a green photosensitive detector configured to receive a reflected green light resulting from the green spectrum illumination.
 19. The system of claim 1 further comprising a waste collection mechanism configured to collect an ablated portion of the surface.
 20. The system of claim 1 wherein the laser source, the scanning optics, the one or more light illuminators, and the one or more photosensitive detectors are configured as an integrated device.
 21. A laser-based coating removal system to remove a coating from a surface, the system comprising: a. a laser source configured to provide a laser pulse; b. scanning optics configured to direct the laser pulse along a laser path to a first position on the surface thereby ablating a portion of the coating from the first position; c. one or more light illuminators configured to provide a light illumination; d. an illumination path configured to direct the light illumination to the first position on the surface, wherein the illumination path includes at least a portion of the scanning optics; e. a photosensitive detector configured to receive light reflected from the surface as a result of the light illumination and to measure the reflected light; and f. a color sensing path configured to direct the reflected light from the surface to the photosensitive detector, wherein the color sensing path includes at least the portion of the scanning optics.
 22. The system of claim 21 further comprising a control logic circuit coupled to the laser source, the scanning optics, and to the photosensitive detector, wherein the control logic circuit is configured to provide control signals to the laser source, the scanning optics, and the photosensitive detector.
 23. The system of claim 22 further comprising a comparator coupled to the photosensitive detector and configured to compare the measured reflected light with predetermined parameters to determine if the coating is removed from the first position on the surface.
 24. The system of claim 23 wherein the control logic circuit is configured to provide a first control signal to the scanning optics to direct the laser pulse to the first position on the surface if it is determined that the coating is not removed from the first position.
 25. The system of claim 24 wherein the first position and each successive position on the surface is determined according to a coating removal pattern.
 26. The system of claim 25 wherein if it is determined that the coating is not removed from the first position, or one or more successive positions, then the control logic circuit is configured to maintain a record list of each position at which the coating is not removed such that an additional laser pulse is directed to each position listed in the record list.
 27. The system of claim 21 wherein the scanning optics include one or more reflecting scanners.
 28. The system of claim 27 wherein the one or more reflecting scanners comprise a lens and mirror array.
 29. The system of claim 21 wherein the scanning optics include one or more refracting scanners.
 30. The system of claim 29 wherein the one or more refracting scanners comprise a lens and prism array.
 31. The system of claim 21 wherein the scanning optics include focusing optics.
 32. The system of claim 21 wherein the scanning optics include a telecentric scanning lens.
 33. The system of claim 21 wherein the one or more light illuminators comprises a single wide spectrum illuminator.
 34. The system of claim 33 wherein the photosensitive detector comprises a sensor configured to measure a relative lightness of the surface.
 35. The system of claim 33 wherein the photosensitive detector comprises a spectrophotometer sensor configured to measure the reflectance of the reflected light at a plurality of different wavelengths.
 36. The system of claim 21 wherein the one or more light illuminators comprises a red spectrum illuminator configured to provide a red light illumination and a blue spectrum illuminator configured to provide a blue light illumination.
 37. The system of claim 36 wherein the photosensitive detector comprises a photosensitive sensor configured to temporally separate a reflected red light resulting from the red spectrum illumination and a reflected blue light resulting from the blue spectrum illumination.
 38. The system of claim 36 wherein the photosensitive detector comprise a red photosensitive detector configured to receive a reflected red light resulting from the red spectrum illumination and a blue photosensitive detector configured to receive a reflected blue light resulting from the blue spectrum illumination.
 39. The system of claim 21 further comprising a waste collection mechanism configured to collect an ablated portion of the surface.
 40. The system of claim 21 wherein the laser source, the scanning optics, the one or more light illuminators, and the one or more photosensitive detectors are configured as an integrated device.
 41. The system of claim 21 further comprising a beam splitter configured to direct the reflected light away from the laser path and toward the photosensitive detector.
 42. A method of removing a coating from a surface, the method comprising: a. providing a laser pulse; b. directing the laser pulse along a laser path to a first position on the surface, whereby the laser pulse impinges the first position on the surface thereby ablating a portion of the coating from the first position; c. providing a light illumination along at least a portion of the laser path and to the first position on the surface; d. detecting a reflected light directly from the surface, the reflected light resulting from the light illumination impinging the surface; and e. analyzing the detected reflected light.
 43. The method of claim 42 further comprising comparing the analyzed reflected light with predetermined parameters to determine if the coating is removed from the first position on the surface.
 44. The method of claim 43 further comprising providing and directing a subsequent laser pulse to a second position on the surface.
 45. The method of claim 44 further comprising determining the first position, the second position, and each successive position on the surface according to a coating removal pattern.
 46. The method of claim 45 wherein if it is determined that the coating is not removed from the first position, then the method further comprises maintaining a record list of each position at which the coating is not removed, performing a subsequent coating removal cycle according to the coating removal pattern, and during the subsequent coating removal cycle providing and directing an additional laser pulse to each position listed on the record list.
 47. The method of claim 42 wherein directing the laser pulse along the laser path includes reflecting the laser pulse.
 48. The method of claim 42 wherein directing the laser pulse along the laser path includes refracting the laser pulse.
 49. The method of claim 42 wherein providing the light illumination directed at the first position on the surface comprises providing a plurality of temporally distinct light illuminations.
 50. The method of claim 49 wherein analyzing the received reflected light comprises temporally separating the reflected light.
 51. The method of claim 42 further comprising collecting the ablated portion of the surface. 